Update _apply_preprocessing_gradient in loss_gradient

Signed-off-by: Beat Buesser <[email protected]>

Author: Beat Buesser

art/estimators/speech_recognition/pytorch_deep_speech.py

@@ -492,7 +492,7 @@ def loss_gradient(self, x: np.ndarray, y: np.ndarray, **kwargs) -> np.ndarray:
             results_[:] = list(results)
             results = results_
 
-        results = self._apply_preprocessing_gradient(x_in, results)
+        results = self._apply_preprocessing_gradient(x, results)
 
         if x.dtype != object:
             results = np.array([i for i in results], dtype=x.dtype)  # pylint: disable=R1721